Multicast Routing in AWS

Consider for a moment that you have an application running on a server that needs to push some data out to multiple consumers and that every consumer needs the same copy of the data at the same time. The canonical example is live video. Live audio and stock market data are also common examples. At the re:Invent conference in 2019, AWS announced support for multicast routing in AWS Virtual Private Cloud (VPC). This blog post will provide a walkthrough of configuring and verifying multicast routing in a VPC.

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Lifting the Hood on Cisco Software Defined Access

If you're an IT professional and you have at least a minimal awareness of what Cisco is doing in the market and you don't live under a rock, you would've heard about the major launch that took place in June: "The network. Intuitive." The anchor solution to this launch is Cisco's Software Defined Access (SDA) in which the campus network becomes automated, highly secure, and highly scalable.

The launch of SDA is what's called a "Tier 1" launch where Cisco's corporate marketing muscle is fully exercised in order to generate as much attention and interest as possible. As a result, there's a lot of good high-level material floating around right now around SDA. What I'm going to do in this post is lift the hood on the solution and explain what makes the SDA network fabric actually work.

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Troubleshooting Cisco Network Elements with the USE Method

I want to draw some attention to a new document I've written titled "Troubleshooting Cisco Network Elements with the USE Method". In it, I explain how I've taken a model for troubleshooting a complex system-the USE Method, by Brendan Gregg-and applied it to Cisco network devices. By applying the USE Method, a network engineer can perform methodical troubleshooting of a network element in order to determine why the NE is not performing/acting/functioning as it should.
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Tools for TE with EIGRP

In response to my article about what would cause a directly connected route to be overridden, Matt Love (@showflogi) made a good observation:

What Matt is saying is that longest prefix match (LPM) is a mechanism that can be used to steer traffic around the network in order to meet a technical or business need. This type of traffic steering is called traffic engineering (TE).

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When is a Connected Route Not Used?

I ran into this situation on a recent project and thought it would make an excellent question on an exam. It could be worded something like this:

What is the behavior of a router or Layer 3 switch when a dynamic route is learned that partially overlaps with a directly connected network?

  1. The router reboots
  2. The network reboots
  3. That's um-possible
  4. None of the above
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Label Switched Multicast -- Ethernet Header

I got an interesting email from Ying Lu who had read my posts on LSM: I am curious about the Ethernet DA and codepoint used for multicast MPLS. Previously, I understand that: Ethernet DA is unicast MAC of nexthop of each replication leg. codepoint is 0x8847 However, looking at RFC5332, I am not so sure... Quote: "Ethernet is an example of a multipoint-to-multipoint data link. Ethertype 0x8847 is used whenever a unicast ethernet frame carries an MPLS packet.
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NSF and GR on Nexus 5000

NSF and GR are two features in Layer 3 network elements (NEs) that allows two adjacent elements to work together when one of them undergoes a control plane switchover or control plane restart.

The benefit is that when a control plane switchover/restart occurs, the impact to network traffic is kept to a minimum and in most cases, to zero.

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BRKRST-3014 -- Policy, Complexity, and Modern Control Planes

Presented by: Russ White, LinkedIn

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BRKRST-2042 -- Highly Available Wide Area Network Design

Presented by: David Prall, Communications Architect, Cisco

For reference, David is the "father of IWAN".

This session was not what I was expecting. I was expecting design and architecture, but it was all about features in IOS and IOS-XE (eg, FHRPs, talked about routing protocol timers, PfRv3, BFD). I guess I need to pay more attention to the session code (RST == routing; ARC == architecture).

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BRKIOT-2109 -- Connecting Oil and Gas Pipelines

Presenters:

  • Rick Irons-Mclean, Oil & Gas and Energy Architecture Lead
  • Jason Greengrass, IoT Solution Architect
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